Hypostomus yaku is a species of South American armoured catfish from the family Loricariidae.

[2] H. yaku is unusual when compared to other species of Hypostomus in that it tolerates warm water up to 34 °C (93 °F) and only attains a relatively small size, growing to 70.8 mm (2.79 in) SL.

[2] H. yaku can be distinguished from the other members of Hypostomus, some 180 plus species,[3] by the presence, in mature adults, of hypertrophied odontodes arranged randomly along its flanks and caudal peduncle.

[2] This characteristic is also found in species of other Hypostominae genera, Aphanotorulus, Peckoltia and Squaliforma, but can be distinguished by several keys (see Martins et al.

[2] H. yaku is most similar to two other species found in the same region, H. nigromaculatus and H. paulinus, but can differentiated by a lack of dark spots (versus presence in H. nigromaculatus)[4] and by smaller adult size (70.8mm SL versus 135 mm (5.3 in) SL in H.